Clarify when changing a List to a Set is considered breaking

[roaks3]

Follow-up to #12814

Release Note Template for Downstream PRs (will be copied)

See Write release notes for guidance.

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR hasn't generated any diffs, but I'll let you know if a future commit does.

[melinath]

Exceptions should be documented in https://googlecloudplatform.github.io/magic-modules/breaking-changes/make-a-breaking-change/#in-minor-releases

[roaks3]

@melinath I can move it, but just wanted to mention that personally I wouldn't have found that page. Could you confirm we're happy with the discoverability of this note on that page?

[melinath]

I think we should be consistent about where we document the exceptions - they should either all be on "Make a breaking change" or all be on "Types of breaking changes".

Currently we have them on the "Make a breaking change" page because the idea is that the change is a breaking change, it's just that we make an exception in certain edge cases. Documenting it on "Types of breaking changes" would be more indicating that the change is not considered breaking in all cases.

For me the thing that makes "Make a breaking change" preferable is that any breaking change could be safe in a minor release, as long as it fixes a bug that impacts all configurations that include a field or resource. (And I don't want to add caveats to every item on the breaking change list.)

I could potentially be convinced otherwise; if this is something you feel strongly about we should discuss it offline.